Sue Lowden was at her Las Vegas early voting location as soon as it opened at 10 a.m. Wednesday. But like so many other voters in battleground Nevada, the former state party chairwoman had to wait 30 minutes in a line out the door that had only lengthened by the time she left.

“It’s packed,” Lowden, who lost her bid for the GOP Senate nomination in 2010, said by phone later.

Early voting is exploding in the Silver State, and Democrats so far are the biggest benefactors. The Democratic advantage, coupled with the party’s strong voter registration edge, has party insiders in the state at the very least optimistic about the presidential and Senate contests with just more than a week to go.

“I think that looking at what’s happened so far with the early vote, we’re hitting on all eights,” said Billy Vassiliadis, an informal adviser to statewide Democratic efforts and longtime ally of Senate Majority Leader Harry Reid (D-Nev.).

However, the positive sign for the party comes as the candidates in both races are separated by just 3 points, and as further evidence emerges of the potential for a split ticket. That’s according to a poll released Thursday by NBC News, the Wall Street Journal and Marist College, in which President Barack Obama led Republican presidential nominee Mitt Romney, and appointed Sen. Dean Heller (R) topped Rep. Shelley Berkley (D) for the Senate seat.

Ryan Erwin, who is leading Romney’s efforts in Nevada, called the two statewide contests “margin of error races,” and noted that both parties are actually outperforming the norm so far in early voting. Both Obama and Romney were in the state this week in an effort to boost early turnout.

In Clark County alone, which includes Las Vegas, after the first five days of early voting, more than 150,000 had voted in person and 30,000 had sent in absentee ballots. Through Wednesday, registered Democrats had accounted for 50 percent of the votes cast so far in the state’s largest county, while 33 percent were cast by Republicans and 17 percent by those registered as independents or with third parties.

At 9 points, the Democratic edge is far less statewide when the heavily Republican rural counties and the Northern Nevada swing county of Washoe are factored in. In terms of population, Washoe is the second largest county in the state. Overall, about 23,000 more Democrats have voted early statewide than have Republicans.

“If Democrats end early voting up 80,000 to 90,000 votes in terms of raw turnout numbers, you’ve got a battle,” Erwin said. “If it’s less than that, we feel pretty good. If it’s more than that, you look at it and say, ‘Wow, that’s going to be harder.’”

To some surprise, the early voting pace had not tapered off much from the burst as voting kicked off on Saturday. Not counting Sunday, when early voting locations were closed in all but three counties, daily turnout numbers ranged from almost 50,000 on Saturday to nearly 46,000 on Wednesday.

Berkley and the Democrats running in the 3rd and 4th Congressional districts will clearly benefit from the turnout operation put in place by Reid’s state party and the Obama campaign’s state operation. The question now is whether that’s enough to knock off two Republican incumbents — Heller and Rep. Joe Heck (R) — and win the new district added in reapportionment.

Strategists from both parties said the Senate race specifically has more complications that make predicting it based off early voting numbers unreliable. “It’s a little harder to draft off of the president or off of the party when that race has had 2,000 or 3,000 points a week of television,” Vassiliadis said. “It’s not as if there’s going to be a lot of blind voting as there may be down-ticket.”

The turnout obviously helps her, he added, “But ultimately there is a lot of familiarity with Shelley and Dean.”

Berkley has made a point all cycle to introduce herself to voters in Reno’s Washoe County, which is far removed from her House district in Las Vegas. That’s in contrast to Heller, who is from Carson City in the north but won three statewide elections as secretary of state, represented the largest Congressional district in the country by area for more than four years and has represented the entire state in the Senate for more than a year.

“He is going to over-perform what normal Republicans do in Clark County,” Erwin said. “If Heller wins Washoe County and holds his own in Clark County, he wins this. You start putting the math together — it works out to be a Heller advantage.”

Strategists from both parties said state Speaker John Oceguera (D) will need a significant turnout boost in the 3rd district, which includes much of the Las Vegas suburbs. He’s taking on Heck in a district that’s seen significant ad buys from both national parties in the last two weeks.

“There’s no question that Oceguera has his work cut out for him,” Nevada-based Democratic consultant Dan Hart said.

The 4th district encompasses parts of Clark County, including North Las Vegas, and parts or all of six rural counties. State Senate Majority Leader Steven Horsford (D) has found himself in a much closer race than anticipated against businessman and frequent candidate Danny Tarkanian (R). Democrats still expect Horsford to pull it out.

The Senate race is a far tougher call. The north-south divide is critical in this race, former Nevada GOP Executive Director Dan Burdish said, and what happens in the presidential race is “immaterial” to the Senate outcome.

“Despite the fact that Democrats may get a lot of turnout in Washoe County, they tend to vote Republican if the Democratic candidate is from Clark County,” he said. “And that is just a fact of life.”

As Nevada political expert Jon Ralston noted, while Heller led by 3 points among likely voters in the Marist poll, the Senate race was tied among registered voters. So Berkley’s path to victory could be paved for her if Democrats can capitalize on their 90,000-voter registration advantage, which remains a possible but not certain scenario.

Still, Hart said Democrats are doing so well in early voting that it looks positive for Berkley with just more than a week to go.

“The bigger the turnout, the better off Shelley Berkley is going to be,” Hart said. “I think she squeaks it out.”